A group of disorders that result in excessive or prolonged bleeding
- Age, gender, genetics, and lifestyle as risk factors depend on the cause
Normally, when there is bleeding a blood clot forms to seal the damaged vessel and prevent further blood loss. The clotting process relies on an interaction between blood cells called platelets, circulating proteins in the blood known as clotting factors, and the vessel wall. A lack of clotting factors or platelets will disrupt the clotting process, which may lead to easy bruising, prolonged or severe bleeding after even minor injury, or internal bleeding into muscles, organs, and joints.
Many disorders that cause excessive bleeding are inherited, the most important being haemophilia and Christmas disease and the related disorder von Willebrand’s disease. These conditions occur when the gene that is responsible for a particular clotting factor is abnormal, resulting in either low levels or a complete absence of the clotting factor in the blood.
In thrombocytopenia, there are too few platelets in the blood. This condition can occur as a complication of bone marrow disorders, such as leukaemia and aplastic anaemia, or as a side effect of certain drugs, such as the anticancer drugs used in chemotherapy. Low platelet levels may result from infections, such as HIV infection (see HIV infection and AIDS) or sepsis (see Septicaemia).
Disorders of the liver, where clotting factors are produced, or the intestines, where vitamin K (an essential component of clotting factors) is absorbed, may also result in abnormal bleeding.
What might be done?
Bleeding disorders due to an absence of one or more clotting factors may be treated by regular injections of the missing factors. If the bleeding disorder is due to a drug, the use of that drug may be stopped. In other cases, treatment is aimed at the underlying disorder.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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